Motion Picture Aspect Ratios

He begins working calculus problems in his head as soon as he awakens. He did calculus while driving in his car, while sitting in the living room, and while lying in bed at night.

Figure 1: Movie That Prompted a Discussion of Aspect Ratio.

I love old movies and one of the best is The Quiet Man. I recently picked up the Blu-Ray version and watched it with my wife this weekend. During the movie, my wife asked about the movie's aspect ratio – it is not a widescreen movie. The Quiet Man was filmed in Academy Ratio (1.37:1), a ratio which was standardized by the Academy of Motion Picture Arts and Sciences in 1932. The Quiet Man was released in 1952, a year before the mass introduction of a plethora of widescreen film formats.

Most of the old movies I watch are from 1953 and later, so my wife is used to seeing my old movies in widescreen format. I must admit that I love the widescreen formats and I am drawn to them for my personal viewing – I especially like VistaVision.

I thought it would be useful to review the different aspect ratios used in movies and television here. Let's begin by defining the term aspect ratio.

The aspect ratio of an image describes the proportional relationship between its width and its height. It is commonly expressed as two numbers separated by a colon, as in 16:9. For an x:y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this same length unit, the height will be measured to be y units.

There are an enormous number of aspect ratios that have been used in motion pictures and the Wikipedia has a comprehensive list for those who are interested. I have summarized the major commercial aspect ratios in Table 1. VistaVision is still used quite a bit for movie's with special effects (e.g. Interstellar).

Television aspect ratios are more limited and are listed as follows (source):

• 4:3

  Standard aspect established for televisions established back in the late 1930s with the NTSC.

• 16:10

  Close to the Golden Ratio, this is used by a number of tablets.

• 16:9

  Standard HDTV aspect ratio.

• 21:9

  One of the lesser-known extra-wide video standards.

• 256:135

  One of the 4K display ratios.